Generally, where food and drink, in particular, food, is stored or packed in a sealed or vacuum state so that it cannot come into contact with air or oxygen, it is possible to prevent the food from being oxidized or rotting, to considerably lengthen the storage period of the food, and to maintain the freshness and intrinsic smell of the food for a prolonged period of time.
For such a purpose, a zipper pack has been proposed in which a zipper consisting of female and male zipper members is provided at an opening of the pack, so as to conveniently seal the opening. However, this zipper pack has a problem in that the seal may be easily collapsed by external pressure. Also, there are problems of a difficulty in manufacture and an increase in manufacturing cost.
Also, a hinged sealing device has been proposed which has two members hingably connected to each other, and adapted to clamp the opening portion of a pack therebetween. However, this hinged sealing device cannot provide a reliable seal. Furthermore, it is inconvenient to use this sealing device. In particular, there is a problem caused by the structure of the sealing device in that the seal at the middle portion of the sealing device is weak.
Meanwhile, general vinyl packs made of a polyethylene (PE) film or polypropylene (PP) film can be inexpensively and easily manufactured. However, such a vinyl pack does not have a dense structure, so that smell molecules of the contents in the vinyl pack may pass through the vinyl pack, thereby emitting foul odors.
When the opening of such a vinyl pack is widened to put a material into the vinyl pack, it may not be maintained in the widened state. For this reason, where a soup containing solids is to be put into the vinyl pack, there is a problem in that the liquid or solids of the soup may be smeared on the outer surface of the vinyl pack around the opening or flow along the outer surface of the vinyl pack, thereby staining the vinyl pack. Such a problem is mainly caused by the fact that both the general vinyl pack and the vacuum vinyl pack have an insufficient rigidity to maintain the opened state of their openings, or they have no means for maintaining the opened state of their openings.